Toothed cutting impeller for pulping solid materials in liquid suspension



Jan. 12, 1954 G B c o so JR 2,665,853

TOOTHED CUTTING IMPELLER FOR PULPING SOLID MATERIALS IN LIQUIDSUSPENSION Filed Aug. 25, 1951 INVENTOR. 650265 B. NIcHqLsoNJR. BY 3 Wiw ATTORNEYS V mounted for rotation Patented Jan. 12, 1954 UNITED STATESTOOTHED CUTTING IMPELLER FOR PULP- ING SOLID MATERIALS IN LIQUID SUS-PENSION George B. Nicholson, Jr.,

to The Black-Clawson Company, Hamilton, Ohio, a corporation of OhioApplication August 23, 1951, Serial No. 243,326 6 Claims. (01. 241 -298)This invention relates to apparatus for pulping or disintegrating solidmaterials in liquid suspension.

The invention has special application to apparatus for mechanicallydisintegrating or pulverizing solid materials such particularly asmaterials which are not soluble in water but are readily handled inwater suspension and which it is desired to reduce to particles ofrelatively small size without crushing or bruising. For example, theinvention has been practiced successfully with varied materials of thisgeneral nature such as chunks or large particles of cellulose acetatefor reduction to substantially uniform small particle size, large piecesof orange peel for reduction to slurry form in preparation for furtherprocessing, and particles of animal fat or fatty tissue fordisintegration of the fat globules and connecting tissues to facilitaterendering of the fat, and the invention has as a major objective theprovision of apparatus for efiect-disintegrating or pulverizing of solidmaterials of the above type under controlled conditions givingsubstantially small particle sizes at economical cost in terms of therequirements of both power and operating time while avoiding crushing orbruising of the material.

This general objective is accomplished in accordance with the inventionby treating the solid materials in liquid suspension in pulpingapparatus provided with a chamber adapted to contain a quantity of thesuspension and equipped with an impeller having special structural andoperational features such that it causes continuous radial circulatingmovement of the suspension and at the same time subjects the solidparticles therein to repeated cutting action by a plurality of rapidlymoving blades which operate both to sever the particles and also tocause these severed particles to be comingled at high speed and withhigh turbulence creating a further disintegrating eifect. Thus bothinertia and hydraulic pressure cooperate with the cutting blades inperforming the disintegrating operation, and since both of these factorsdecrease as the sizes of the particles become smaller, it is possible inthe practice of the invention to establish a desired size of theparticles and to reduce all the solid material to this predeterminedsize with'a high degree of uniformity.

It is accordingly an object of the invention to provide disintegratingapparatus for operation on solid materials in liquid suspension whichincludes an open chamber having an impeller therein and formed with aFulton, N. Y., assignor plurality of thin blades arranged in suchrelation to its rotational axis that as the impeller rotates and causesthe suspension to circulate continuously across its surface in generallyradial directions, the cutting blades intersect the path of travel ofthe suspension substantially at right angles to effect repeated cuttingaction on the particles coupled with a high propulsive action causingthe cut particles to rush against each other for further disintegration.

Another object is to provide disintegrating apparatus of the abovecharacter for solid materials in which the impeller is formed with twoor more radially spaced circumferential rows of cutting blades adjacentits periphery, and in which adjacent blades in each row are arranged atdifferent angles to the rotational axis of the impeller to give a highnumber of blades with intervals therebetween in each row for highcutting action with minimum bruising.

It is also an object of the invention to provide an impeller fordisintegrating apparatus as outlined above which-may be readilyfabricated from sheet metal in different sizes and different numbers ofrows of cutting blades and relative sizes of blades in accordance with agiven material to be treated and the desired conditions of operationthereon.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawi gs and the appendedclaims.

In the drawings Fig. 1 is a view partly in side elevation and partly invertical section showing pulping apparatus including an impellerconstructed in accordance with the invention;

Fig. 2 is a plan view of the impeller;

Fig. 3 is an enlarged section on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary view of one of the rows of blades on theimpeller;

Fig. 5 is an enlarged fragmentary view showing structural details of onof the cutting blades; and

Figs. 6 and 7 are enlarged fragmentary sections on the lines 6-6 and 1-!respectively of Fig. 4.

Referring to the drawing, which illustrates .a preferred embodiment ofthe invention, Fig. 1 shows a pulping apparatus generally of the construction disclosed in Martindale Patent 2,371,837, issued March 20,1945, to the assignee of this application. This pulper includes a tub orvat having a cylindrically extending upper wall portion l0, an inwardlytapered lower wall tom of the tub and above. its bottom ,.w,al1 '.ihev

rapid rotation of the irripeller;..2il .:vprovides "an effectivecirculation outwardly and then upwardly along the outer portions of thetub with a return downflow towards theriimpeller, as indicated by thearrows, and vanes .oi plate's z It are-mounted on the wall portion 4 toguide the upward now of the pulp or stock. Adjacent thejbottom of thetub is an annular chamber or compartment 22 partitioned from the spaceabove the' impeller by a perforate extractor plate 25 of fruston l rforv wh h-perm ts t e passage ofxthe 1 fi p t e .rccm arment...nafromewhich it -may be withdrawnas desirec l-by way, of the;conduit 26 shown as proyidedgwitha shutoffvalve 21.

- Ihe impeller :1ncludes a main plate orgdisk ;having ashaftportionqtlior. connectionv to v the drive for rotation as-describedabout its central axis 33.. ,Anadapterplate35. is secured to theupper-surface of plate-30 by meanssuch, as

bolts 36, and the impeller..-is alsoprovided on its upper surfacepwithea plurality. of, nested; disks each formed with a, row of cuttingblades around its; periphery. Threeof these disks are, shown and areidentified ;as .40-, ligand 42., respectively,

and they are of difierent;,diameters and-mare mounted on the; impellerby-.-..means of; thebolts .7 36, and a central holddowrr plate 44;. ;Aplurality ofcurved vanes are ;shown; as, mounted near the center oftheimpeller to. serve as pumping the diameter of the disk and the desirednumber of teeth, satisfactory results having been obtained with thisdimension varying from approximately of an inch to two inches or more.

As one example of the type or disintegrating or pulverizing action forwhich .theapparatus ofthe present invention has proved highlysuccessful, it has been used for reducing large chunks of celluloseacetate to a substantially uniform small. particle size. In one seriesof test 'runs :for: this purpose, using pulping apparatusbf-the typeshown in Fig. 1 having the tub five feet in diameter was used, thecellulose gacetate particleaiwhich varied from sizes of the order-ofahead of cabbage down to approxi- --mately-=the size of a grain ofsugar, were added 1 ina solutionofiwater and glacial acetic acid,

with the total weight of the cellulose acetate -varyingfrom 240 to 430pounds and with the total volume of the suspension being of the order013-400;: gallons: In. some gruns;-=.the-: impeller was :constructedas;shown:in,Fig. 3'zwithgth-ree; disks respectively 18, 24 and 30 inchesin diameter, and inyother runs only the, smaller='-;twd31iisks wereused. In .each case with the :;impeller;; ro-

. tatingat a rate giving a'peripheral speed 0f155100 feet per ,minutefor the largest disk, reduction of the cellulose acetate to anextent-such "that -:-less than 2% was retained. on a 5-meshrscreen wasaccomplished infrom 10 to 15.: minutes with ---economica1 "expenditureof power.

' Another use for which -.apparatus in accordance cwiththe inventionhasbeen satisfactorily. used is the mechanical, disintegration of theresidual fatty tissue-resulting: from rendering raw; animal vanes urgingthe pulp .-.rgadi ally,outward across 40 ,.tissue, which comprisesapproximately-70 %.rfat, is moredifiicultto break down.llighlyvsatisfac- .the surface;of. the.plate as the, impellergrotates inoperation, ,the use; ofgthese yanes bein opnal p d up n v: he. particuar. materials and operating conditions. desired.

. The construction and; arrangement of the in;

. .dividual blades on each -ofthe disks or1plates .40-42areshowninjfijigsyd to 7.,Thesehlades 50 are generally saw-toothed inshapa-yandzeach is formed on itsleading -edge with; ;,s harp,ened

. c tt ed 5 ae enqinet initia r..-. enerally disk vary .with .,th ediameter Of'rthQ. disk butnin generalsatisfactory results have beenobtained. 7 with pulping apparatus of, the type, shown in Fig. lQfdifierent sizes; requiring impellerslof correspondingly ,di ffer,ent;-., diameters,;-; .wherein the blade disks =,arefor1 ned of ;l 1gauge;.-stainless is approximetfily yi otwan inch. in.;length;and isinclined. slightly backwards; foneexamplecabout 2", from a radius:-traversing;-its:.zinnermostcend.

The length of; the.cbladesgmeasured:along the eline flamesbe.-;varied.in accordance with 20 .minutes,- -but the :remaining adiposefatty toryphysical disintegration of, this fatty tissue and, releaseof..the remaining fat has been-.ac-

.complished in a pulpingrapparatust constructed as described .above,with the .rapid' rotating impeller blades acting to disintegrate.the-tissues and .thereby to. rupture .the fat cells and: permit releaseor thefat and recovery of- -thec-valuable ,proteinresidue. withoutdamage such: as would tend tore's'ult fromtheprolonged heating usuallyrelied onfor, this purpose.

{Tests of, the above character indicate-that in the operation of theapparatus of the invention,

'the peripheral. speed 'ofthe cutting blades is of material importancein'obtaining'eff'ective. cutting action with alminimumf or bruising. Ingeneral the preferred blade speedappearsto be not .substantially lessthan approximatelyfififidfeet.per

- minute, .computed for the outermost row ofblades where'more than onerow, of blades isused, speeds of this" order having. beenfoundhighlysatisfactory for 'suchiwidely differing materials aslthecellulose acetate" and animal fat residue. mentioned'above. In'thisspeed range,v thepaths' of the radially circulating'particles and theblades -crossat angles-ofthe maximum sizeyand the relative speeds ofboth particlesand blades are sufficiently high for-the"desiredshearingaction ofthe blades on the -particleswithout bruisin tion, it is to beunderstood thatthe invention is not limited to this precise form ofapparatus, and that changes may be made therein without departing fromthe scope of the invention which is defined in the appended claims.

What is claimedis:

1. An impeller adapted for use in disintegrating solid materialssubstantially without bruising thereof in apparatus of the characterdescribed including a chamber adapted to contain a quantity ofrelatively large particles of said materials in liquid suspension,comprising a plate adapted for rotation in said chamber about an axissubstantially normal to said plate to subject said suspension tocentrifugal force causing said suspension to circulate radially acrossthe surface of said plate, means forming a plurality of relatively thincutting blades adjacent the periphery of said plate and extending atsubstantial angles with respect to the plane of said plate, each saidblade having a, cutting leading edge thereon facing in said direction ofmovement to cross said radially circulating suspension at relativelylarge angles for effective shearing action on said particles therein,said blades being generally saw-toothed in shape and extending generallyin line with the direction of movement thereof with said impeller topresent minimum surface area to the radial flow of said suspension inuse for avoiding bruising of said solid materials therein, and saidblades being located adjacent the periphery of said plate to providesubstantially maximum linear velocity therefor for a given angularvelocity of said plate.

2. An impeller adapted for use in disintegrating solid materialssubstantially without bruising thereof in apparatus of the characterdescribed including a chamber adapted to contain a quantity ofrelatively large particles of said materials in liquid suspension,comprising a plate adapted for rotation about an axis substantiallynormal thereto in said chamber to subject said suspension to centrifugalforce causing said suspension to circulate radially across the surfaceof said plate, means forming a plurality of circumferential rows of thincutting blades concentrically arranged in radially spaced relation onsaid plate and extending at substantial angles with respect to the planeof said plate, each said blade having a cutting edge facing in thedirection of movement thereof with said impeller and having the radiallyinner edge thereof substantially tangent to the same circle concentricwith said plate as the other said blades in the same said row therewithto align the remainder of said blade generally with said direction ofmovement to avoid bruising of said solid materials in use, and theoutermost of said rows being located substantially at and in saidtangential relation with the periphery of said plate to provide maximumlinear velocity therefor for a given angular velocity of said plate.

3. An impeller adapted for use in disintegrating solid materialssubstantially without bruising thereof in apparatus of the characterdescribed including a chamber adapted to contain a quantity ofrelatively large particles of said materials in liquid suspension,comprising a plate adapted for rotation about an axis substantiallynormal thereto in said chamber to subject said suspension to centrifugalforce causing said suspension to circulate radially across the surfaceof said plate, a disk of sheet material secured to the upper surface ofsaid plate, said disk having a plurality of cutting blades formed alongthe periphery thereof eachhaving a cutting edge thereon facing in thedirection of movement thereof with said impeller, said blades being bentout of the plane of the remainderof said disk along lines substantiallytangent to a common circle to cross said radially circulating suspensionat relatively large angles for effective shearing action on saidparticles therein and to locate the remainder of each said bladegenerally in line with said direction of movement thereof, and saidblades being generally saw-toothed in shape with, said cutting edgesthereof generally radiallyarranged with respect to said plate axis formaximum cutting action on said solid ma-v terials while presentingminimum surface area to theradial flow of said suspension to avoidbruising of said solid materials therein.

4. An impeller adapted for use in disintegrating solid materialssubstantially without bruising thereof in apparatus of the characterdescribed including a chamber adapted to contain a quantity ofrelatively large particles of said materials in liquid suspension,comprising a plate adapted for rotation in said chamber about an axissubstantially normal to said plate to subject said suspension tocentrifugal force causing said suspension to circulate radially acrossthe surface of said plate, a disk of sheet material secured to the uppersurface of said plate, said disk having a plurality of cutting bladesformed along the periphery thereof and bent out Of the plane of theremainder of said disk, and each said blade having a cutting edgethereon facing in the direction of movement thereof with said impellerto cross said radially circulating suspension at relatively large anglesfor effective shearing action on said particles therein, adjacent saidblades being arranged at different angles to the plane of said disk toprovide an interval between alternate said blades.

5. An impeller adapted for use in disintegrating solid materialssubstantially without bruising thereof in apparatus of the characterdescribed including a chamber adapted to contain a quantity ofrelatively large particles of said materials in liquid suspension,comprising a plate adapted for rotation in said chamber about an axissubstantially normal to said plate to subject said suspension tocentrifugal force causing said suspension to circulate radially acrossthe surface of said plate, a plurality of superimposed disks of sheetmaterial secured to the upper surface of said plate, said disks beinggenerally circular and each being of smaller diameter than the adjacentdisk therebelow, each of said disks having a plurality of cutting bladesformed along the periphery thereof and bent out of the plane of theremainder of said disk, and each of said blades having a cutting edgethereon facing in the direction of movement thereof with said impellerto cross said radially circulating suspension at relatively large anglesfor effective shearing action on said particles therein.

6. An impeller adapted for use in disintegrating solid materialssubstantially without bruising thereof in apparatus of the characterdescribed including a chamber adapted to contain a quantity ofrelatively large particles of said materials in liquid suspension,comprising a plate adapted for rotation in said chamber about an axissubstantially normal to said plate to subject said suspension tocentrifugal force causing said suspension to circulate radially acrossthe surface of said plate, a plurality of superimposed disks of sheetmaterial secured to the upper surface of said plate, said disks beinggenerally circular

